A friend in a similar situation was referred to a sleep clinic and it seemed to help. Maybe it is worth exploring these options with the GP. Stages do pass, but it can be difficult at the time, the health professionals need to supply them with some coping strategies too.

It must be very hard for the parents. Not sleeping and working outside the house every day, makes it surely tiring. Difficult to know what to do in such a situation.
None of the parents can take a time off from work to stay more with the kid?

Perhaps (after checking with your in-laws) you could have a chat with the other grandparents and let them know how difficult a time the parents are having at the moment. If they are unwilling to help because they don’t want sibling rivalry, I think they need to have a chat with both children and explain. I’m sure the sibling wouldn’t bear any grudges!

Wow that sounds very hard on the parents and you suffering from afar. I think it sounds like they are getting all the right medical advice to make sure that the baby is ok, and the diagnosis that it is a “stage that will pass” is probably accurate (perhaps its now teething problems?). With our twins it was also very difficult with sleep (and we also had no family around to help, ever) and yes it took YEARS and YEARS to get sleep back on track…. I don’t know what the parents can do to make things easier for themselves, short of seeing a doctor for their own health/relationship needs and taking some leave (sick leave? unpaid leave? holiday) to “catch up”. Getting on-going professional advice about settling the child should obviously happen too. Friends can also be supportive (if family is not around) but I don’t think it does extended family relationships any long term good to expect them (or you) to be the solution. Good luck.